A battle has erupted in Tanzania over the future of 30,000 Maasai people who claim the expansion of a big-game hunting reserve for foreigners will lead to their eviction from ancestral lands.

Tanzania's ministry of tourism announced this week that it will set aside 1,500 square kilometres bordering the Serengeti national park for a "wildlife corridor". The Maasai will as a result be prevented from getting to their pasture land in the corridor, destroying their traditional nomadic cattle-herding lifestyle. Access will however be granted to a Dubai-based luxury hunting and safari company.

Daniel Ngoitiko, a Maasai politician representing part of the corridor, said the announcement amounted to an existential threat for thousands of Maasai tribespeople. "My people's livelihood depends on livestock totally," he said. "We will die if we don't have land to graze."

NGOs say nearly all of the Maasai living in Loliondo district, where the proposed corridor will be, rely on cattle herding for food and to raise money for expenses such as school fees.

Fifty-five Maasai leaders have petitioned the government against the corridor, which would place out of bounds savannah that is lush and grassy in the wet season and dusty scrubland in the dry. They have vowed to resign their posts as local administrators at a mass rally and protest in the Loliondo town of Wasso on Tuesday. Ngoitiko, who wraps himself in the traditional bright red cloth of the Maasai, will march 20km with his constituents to the demonstration.

Ngoitiko said violence could not be ruled out if the government were to proceed. "We will fight against it until the last person is gone," he said.

Despite the passionate resistance to the proposals, the Tanzanian government appears determined to push ahead with the proposed corridor. The minister for natural resources and tourism, Khamis Kagasheki, told one newspaper this week: "If the civic leaders want to resign, they can go ahead. There is no government in the world that can just let an area so important to conservation to be wasted away by overgrazing."

Samwel Nangiria, government programme manager for a group of local NGOs, told the Observer that the Maasai lifestyle, which forbids eating wild game, is harmonious with nature. "The government does not appreciate the way that the Maasai are living with wildlife," he said. "They've been using it for centuries, living with wildlife all over."

The Maasai have followed seasonal rains with their cattle across what is now northern Tanzania and southern Kenya since pre-colonial times. But they have been gradually squeezed out of their territory. The process began in 1959 when the colonial British evicted the tribe from the Serengeti.

"My grandfather was born in the Serengeti where the national park is," Ngoitiko said, arguing that the idea of further relocation was unacceptable. "The land we are claiming is ours because we inherited it from our parents."

Today, of the million-plus Tanzanian Maasai population, at least 66,000 live in the 4,000sq km Loliondo district. The proposed corridor will reduce their land by nearly 40%. The Loliondo highlands are nestled between two jewels of Tanzania's tourist industry – the Serengeti national park to the west and the Ngorongoro conservation area (NCA) to the south. To the east lie the salt flats of Lake Natron, while to the north is the Kenyan border.

Crucially, the reduction in land access would come at a time when climate change is already placing the tribe's lifestyle under pres sure. Jill Nicholson, programme director for local NGO the Women's Pastoralist Council, said: "The rainy seasons are coming later and that's putting stress on water sources."

The highlands are crucial for the June to November dry season.

"The area which is being established in the corridor is used in the dry season grazing," said Nangiria.

"This is the time they need it most so they can have a fallback. Another reason is the wildebeest are coming to calve in Loliondo, so the Maasai have to have access to the highland to keep their cattle away from possible diseases brought by the migrating wildebeest."

The principal hunting outfit which will be able to exploit the corridor is the Ortello Business Corporation of United Arab Emirates. The OBC has operated in Loliondo for 20 years, flying over high-profile clients such as Prince Andrew and the United Arab Emirates royal family on 747s which land on a private airstrip. But their clients' wealth has not filtered down to the Maasai.

Ngoitiko said the hunting lodges did not employ local people, and skirmishes had broken out between herders and OBC security.

In 2009, Maasai and national police clashed after the government tried to force evictions, allegedly to allow the OBC to hunt. Ngoitiko's younger brother Paul said he lost 50 cattle because they could not reach pasture. Paul remembers how losing livestock, a source of identity for Maasai men, broke his father's will. "During the morning he would ask, 'how many livestock have died today?' When you mentioned the number he didn't even speak."

Paul also claims that police burnt down his family's bomas – homes made of mud, thatch, and cow dung. After protests, the government has allowed the people to return, but a court case is still in progress to decide their future.

The government tried to evict Maasai from Loliondo again last year, but backed down after an outcry led by international advocacy group Avaaz. According to campaign director Ian Bassin "nearly a million people called on [Tanzanian president Jakaya] Kikwete to stop the evictions of the Maasai. The government is responsiveto global opinion."

Kikwete has a record of dismissing the Maasai lifestyle. This month, he told a group of pastoralists that "living a nomadic life is not productive".

Paul Ngoitiko disagrees, and on Tuesday he will march with his people in protest. "We have our way of living," he said. "Without land we cannot keep livestock, and without livestock it is a kind of death."